These two volumes present the results of fieldwork conducted by Tertia Barnett from 2004–2009 in the Wādi al-Ajāl (Libya). The first volume provides a general synthesis in three sections: 1) presentation of Saharan rock art in general; history of discoveries and research; climate, environment and human activities in the Holocene Sahara; state of knowledge on the chronology. 2) Presentation of the method adopted for collecting data; results of the surveys; subjects and themes observed. 3) Analysis of the location of the engravings; study of their relationship with the ‘cultural landscape’; concluding remarks. Two appendices are devoted to pre-pastoral and pastoral sites, and to the 3D modelling of several engraved panels respectively. The second volume makes available the totality of the observed data, describing each panel individually. For each one, the inventory indicates its number and geographic position, then gives a detailed description, specifies its orientation, its location in the valley and its degree of inclination, before indicating the stylistic affiliation of the engravings observed. The two books are enhanced by a large number of photographs, surveys and maps, in a very careful presentation and a pleasant layout.